198 THE MICROSCOPIST. 



are designed to move by tendon, aponeuroses, or some form 

 of fibrous tissue. The organs or muscles thus formed are 

 generally solid and elongated, but sometimes expanded. 



Involuntary or unstriped muscular fibres are flat bands 

 or spindle-shaped fibres with nuclei, which may be re- 

 garded as the remains of the formative bioplasm (Plate 

 XX, Fig. 153). They are usually transverse, or interlace 

 with, each other on the walls of cavities and vessels. In 

 the heart the fibres, though involuntary, are striped and 

 branching. Striped fibre varies from e ' th to Y^^th inch 

 in diameter. It is largest in insects, in which individual 

 fibrils may be readily obtained, especially from the thoracic 

 muscles. They are generally found in bundles of fibrils, 

 splitting longitudinally or in disks, and each bundle is 

 inclosed in a sheath or sarcolemma (Plate XX, Fig. 154). 



The transverse striation of muscle is subject to much 

 variation, and the precise nature of the sarcous elements 

 which produce the appearance is yet a matter of dispute, 

 but in all probability the ultimate elements are sarcous 

 prisms or particles imbedded in a homogeneous mass, and 

 by their mutual attraction, excited by various stimuli, 

 the contraction of the fibre takes place. 



For the purpose of observation, the connective tissue 

 may be removed from muscular fibre by gelatinizing it 

 with dilute sulphuric acid, and dissolving it at a temper- 

 ature of 104 F. The nuclei of muscular fibre are seen 

 after treating with acetic acid, and may be stained with 

 carmine fluid, etc. 



2. Nerve-tissue. The term nerve was applied by the 

 ancients to tense cords, as bow-strings, musical strings, 

 etc., and was appropriated to the fibres now called nerves, 

 because they deemed them to operate by tremors, vibra- 

 tions, or oscillations, another instance of wrong naming 

 of structure from an opinion respecting function. Hip- 

 pocrates, Galen, and others, however, thought nerves were 



